You can try either cake mix playdough with a white cake mix, or kool-aid playdough without any kool-aid. Either one should be as white as the flour and salt you use. (Those are my two favorite recipes. I find them to work virtually every time and make something that's nice, not sticky.)

Edible Play Dough:
1 c. peanut butter 1 c. corn syrup
1 1/4 c. powdered sugar 1 1/2 c. dried milk
Knead ingredients together until the dough is the consistency of modeling clay. Make shapes or letters with it and let it dry. Store let overs in plastic. Lick your fingers after you are done. Shapes and letters are edible. This is another favorite of my grandchildren.